Combined toggle and hydraulic press



Oct. 27, 1942. J. PAwLsKl 2,299,845 COMBINED TOGGLE AND HYDRAULIC PRESS Filed Jan. 29, 1941 4 sheets-sheet 1 Gttomcgs Oct. 27, '1942, J. |=Aw| osK|v I COMBINED TOGGLE AND HYDRAULIC PRESS Filed' Jan. 29. 1941 4 Sheets-Sheet 2 Patented Oct. 27, 1942 COMBINED ToGoLE AND HYDRAULIC mass John Pawloski, Pontiac, Mich., assignor to General Motors Corporation, Detroit, Mich., a cor poration of Delaware Application January 29, 194i, seriaiNo. 376,508

(ci. inse-3s) 8 Claims.

My invention relates to a combined toggle and hydraulic press wherein the periphery of a sheet metal blank to be operated upon is clamped between certain elements of the press and held preparatory to a drawing or shaping operation performed upon `the blank, by certain toggle mechanism which is separate and independent in structure and operation from a hydraulically operated lower die which is forced against the blank thus held and into an upper die member, to thereby draw or shape said blank; and the object thereof is to provide a simple, compact and efficient press of limited capacity designed for use under conditions and in localities where large volume of product is not required and one which at the same time may be manufactured at a minimum of cost, which will be light in weight so that it may be readily transported and installed in remote localities, and which may be easily taken down for shipment and re-erected in a new location by y workmen of ordinary skill.

My improved press requires less floor space than heretofore; it is of much less total volume than former presses and, being low in height, re,- quires a minimum of head-room; it is self-contained and requiresno specially designed foundae tion; and, being light and of reduced volume, it may be easily moved about on a shop floor as may be required.

My improved press is readily usable to produce devices in the nature of formed or embossed sheet metal panels which require varying depths of drawing because the hydraulically operated plunger which accomplishes the drawing or shaping of the sheet metal part and the plunger whichoperates it are independent, structurally and functionally, from other parts of the press; and the adaption of the press to various depths of drawing requires the use of no spacing or bolster blocks such as have been necessary heretofore, to adapt existing presses for various degrees of depth of drawing.

With. the above and other objects of invention in view, my invention consists in the improved combined toggle and hydraulic press illustrated inthe accompanying drawings, described in the following specification land particularly claimed; and in such variations and modifications thereof, within the scope of the concluding claims, as will be obvious to those skilled in the art to whichmy invention relates.

In the drawings wherein the preferred `form of my invention is illustrated:

Figure 1 is a View showing my improved press the upper die member carried thereby being shown in labout theiruppermost position.

Figure 2 is a View showing the same in end elevation as seen from a position indicated by the line 2 2, Figure l; the platen and upper die having been lowered against a sheet metal blank resting upon the lower clamping ring, the toggle mechanism not yet having been straightened to subject the blank to increased pressure due to the action thereof.

Figure 3 is an illustrative view showing the upper `die member just before it contacts with a l sheet metal blank resting upon the lower clamping ring.

Figure l is a view showing the upper die as pressed against the sheet metal blank preparatory to the drawing operation to be performed thereupon. v

Figure 5 is ya View showing the lower die member as having beenforced upward and into the upper die member to draw or shape the sheet metal blank.

Figure 6 is a fragmentary view showing the toggle mechanism and adjacent parts shown in Figure 2, the toggle mechanism having been straightened tosubject the sheet metal blank to increased clamping action just before the drawing operation contemplated in Figures 4 and 5.

Figure 7 is a fragmentary view showing the toggle mechanism as seen from aplane indicated by the line 1 1, Figure 6, looking down.

Figure 8 is avew showing a detail of certain latching and unlatching'mechanism-shown more completely in Figures 9 and 10.

Figure 9 is aview showing said latching and unlatching mechanism more completely, and as seen from a horizontal plane indicated by the line 9--9,Figure 1, looking down.

Figure l0 is a viewshowing a section upon a vertical` plane indicated bythe line lil-l0, Figure 9. y

Figure 11 is a fragmentary View showing how the means for unlatching the platen from the tension rods of the press may be dispensed with, if a slight separation` only of the upper die and lower clamping ring will Isuffice for the drawing operation to be performed by the press.

Figure 12 is a View similar to Figure 1 showing a form of my press adapted for inordinately shallow drawing operation. Y

Referring now to the drawings, the numeral lil designates 'a base which serves as a support for all the parts of my improved press, andv which itself is supported by a suitable concrete or equivin side elevation forthemost part, the platen and 55k aient foundation I 1;' which is ordinarily built in a shallow pit so that the toggle operating cylinders I2, of which there are two, are disposed below the floor level and the upper surface of the stationary bed I3 of the press cornes at such a height that sheet metal blanks to be operated upon may be conveniently placed between the die members of the press as will hereafter appear, and finished panels formed by the dies may be removed from the press. The pit, however, is shallow, ordinarily a foot or so in depth; from which it follows that the press may be disposed wholly above the floor level, especially if a low platform is provided for the operator to stand on.

rThe base IE) has a cylinderl I4 vwhich extends upward therefrom to a level slightly below the upper surface of the bed I3, and has also intermediate laterally extending arms I5 which support the fixed bed I3 and to which the bed is fastened; said bed being shown as comprising a plurality of I-beams arranged parallel with one another and which bed, as will be appreciated, is thus supported from the base I0 through the laterally extending arms I5. The base structure is shown as provided with vertically extending ribs I6, as many as may be deemed necessary, to distribute the stresses to which it is subjected when the press is in use more uniformly through out the structure thereof, as will be understood.

rPhe numeral l1 designates a lower blank supporting and clamping ring member which rests upon and is supported by the bed I3, and is therefore stationary and fixed in position; and I8 is a reciprocating lower die member within said ring member and movable vertically therein from its lowermost po-sition shown in Figures l, 3 and l into an uppermost position shown in Figure 5. This member is called a ring member because it ts closely about the die member I8, although it as well also as the said die member are commonly of general rectangular rather than of circular or truly ring-like form. The lower die member I8 is supported upon the upper end of a reciprocating plunger I 9 which operates within the cylinder Id, to which end a liquid under pressure is supplied thereto through a conduit 20. Flow through the conduit 2i) into and out from the'cylinder is controlled by any suitable valve not shown.

The numeral 2| designates a vertically movable upper die member which is secured to the under side of the reciprocating platen 22 of the press, and which member has a clamping ring portion 23 which cooperates with the stationary blank clamping ring member I1 to clamp the periphery of a sheet metal blank 24 between them, as shown in Figures l, 3 and 4; whereupon and as the lower die member I8 is moved upward as aforesaid, and into the upper die member 2|, said sheet metal blank is shaped in conformity with the contour of the upper end of said lower die member. See Figures 1, and 3 to 5. If the upper die member is recessed, as shown, that is if it has an upper wall portion, then the sheet metal blank is ernbossed between the lower die member and said upper wall; whereas if the upper die member is in the form of an open ring then the blank operated upon is pushed upwardly thereinto, thereby drawing the blank but not embossing the central portion thereof as by pressing said central portion against a closed upper wall of a recessed die of the type shown.

The upper die member 2| is moved upward to release the clamping action of the ring portion 23 thereof acting against the upper end of the lower blank clamping ring member I1, by lifting CII means which is separate and independent, structurally, from the press elements per se hereinbefore and to be next described, but which lifting means cooperates with said parts in the operation of the press to carry out the cycle of operation thereof; said lifting means or device being shown as a conventional electrically operated hoist 25, although any suitable lifting means may be used. The numerals 2S, 21, 28 and 29 designate four tension rods which are all alike, and the upper ends of which are connected to the platen member 22 adjacent the four corners thereof to thereby pull said member downward and clamp the periphery of the sheet metal blank 211 prior to the beginning of and during the drawing or shaping operation performed thereupon, as aforesaid; to which end the lower ends of the rods 26, 21 are held between two parallel angle bars 30, 30 by pairs of bolts 3|, so that as said angle bars move downward the rods 26, 21 (as well also as the rods 28, 29 and the platen 22) move downward; thus bringing the clamping ring portion 23 of the upper die member into engagement with the lower blank clamping ring member I1, with the periphery of the sheet metal blank 24 clamped between them as shown in Figure 4. The lower ends of the rods 28, 29 are likewise fastened between two angle bars 3i! I, 33|; and both pairs of bars 30 and 33| are connected with pairs of supports 32, 32 and 32|, 32| secured to the under side of the fixed bed I3 through two toggle mechanisms which are alike at each side of the press, see Figure 1, and one only of which need be described in detail.

Each toggle mechanism shown comprises a, pair of double upper links 33, 33 the upper ends of which are pivotally connected to the supports 32 (or 32|), and a pair of single lower links 34, 34 the lower ends of which are pivotally connected to the bars 30, 3|] (or 33|, 30|). The other and adjacent ends of these several links are pivotally connected to pairs of bars 35, 35 (one pair for each toggle mechanism) extending from one link assembly to the other, so that they move in unison; and 33, 36 are pairs of swinging links (one pair for each toggle mechanism) the left hand ends of which are pivotally connected to a fixed abutment 31 carried by and depending from the supports 32, 32. The right hand ends of the swinging links are pivotally connected to a toggle operating lever 38 (one for each toggle mechanism) which oscillates upon a short shaft 39 the two ends of which are supported in bearings in the bars 35 so that the shaft moves bodily with the bars; and 4|), 40 are pairs of swinging links the upper ends of which are pivotally supported by the supports 32, 32 and the lower ends swing upon the short shaft 39. These links and the pairs of links 33, 33 keep the bars 35, 35 parallel with the supports 32, 32, and with the bars 30, 3U, as the bars 35, 35 move up and down, see Figures 2 and 6; but they are not involved in the lateral movement of the bars which is produced by the lever 38 acting through the swinging links 36, 36. The lever 38 is swung upon the short shaft 39 as a support by a piston rod 4I which is pivotally connected therewith at 42, and which has a piston 43 at its right hand end which operates within the toggle operating cylinder I2; there being two such cylinders, see Figure l, one for operating the toggle mechanism at each side of the press as will be understood. The cylinders I2, I2 are supported by trunnions 4t and brackets 45 which in turn are supported by the supports 30, 30|; and liquid under pressure is supplied to and exhausted from the cylinder through conduits 46, 4B one leading to each cylinder;l` the ow of such liquid being controlled by any suitablevalve mechanism.

Figure l shows the platen `22 as lifted into a high position to permit the removal of `asheet metal blank which has been operated upon, and the substitution therefor of a new unformed sheet. The platen and the tension rods 25, 21, 28 and 29` which at the beginning of upward movement are latched together, so that all move in unison as will hereinafterappear, are moved upward as by the electrically operatedhoist into some position between that shown in Figure 2 and in Figure l; whereupon and as will also appear the latch mechanismreleases the tension rods and the platen is lifted into its highest position shown in Figure 1; high enough to permit the convenient removal of a formed plate from between the lower blank clamping ring I1 andthe upper die member 2I, which is fastened to the runder side ofthe platen and is lifted therewith. Prior to this the die member I8 has beenV permitted to descend so that it lies Within the clamping ring I1, as will be understood. During thisv upward movement of the platen and` the tension rods both toggle mechanisms are made to assume the position in which one of .them is shown in Figure 2` by liquid under pressure ad- `mitted to the left hand ends of the cylinders I2;

by a counter-balancing liquid acting in said ends; by an upward pull of the tension rods if the platen 22 is permanently secured to the upper ends of saidrods (that is, is not'unlatched from them) and needs to be lifted only to the extent of around two inches permitted by the toggle mechanismas when unusually shallow drawing l is to be done; or otherwise so long as both toggle mechanisms take the position shown in Figure 2 preparatory to the` removal of a formed panel ber I8 is forced upward bythe plunger I9, during which movement and during the drawingand shaping operationl the peripheryr of the blank slips and slidesbetween the clamping ring portion and the `upper surface of the blankclamping` ring I1. After the periphery of the sheet metal blank has been clamped as above appears the lower die member I3 is forced upward by the plunger I9, see Figures (i and 5, thus nishing the shaping or` forming operation; the exposed edge of the panel or other object produced being afterward trimmed and smoothed by other machines in accordance with usual practice.

The modication hereinbefore mentioned wherein the platen is permanently secured to and moves with the tension rods will be understood from the fragmentaryviewFigure 1l wherein one of four tension rods 25| is shown as extending through the platen 22|, and as having nuts at its upper end. In this form the platen is lifted by means independent of the press eley ments themselves as is always the case; but the platen is lifted to a lesser extent than is suggestedin Figure 1 thus adapting the press for operation upon blanks which need to be drawn to a slight depth only, and wherein the maximum upward movement of the lower die memand the placing of an unformed plate in the ing function; and if the upper ends ofthe tension rods have not been unlatched from the f platen, or if they are permanently secured thereto (both `of which conditions are exemplified in Figure 3 wherein the platen and upper die member 2I arebut a little ywayabove the blank clamping ring I1) then the weight of the platen androds and asociated parts will overcome the pressure of liquid within-the left hand ends of the cylinders I2 andthe toggle mechanism will move into a nearly straightI or in line position, as shown in Figure 6; the clamping ring portion 23 of the upper l die member then acting to press the periphery of the sheet metal blank operated upon againstlthe upper endof the lower blank clamping .ring I1.

The lowering of the platen and tension rods and associated parts does not result in perfectly straight or in line positions ofthe pairs of toggle `links 33, 34 at the time the periphery of the sheet fluid'under pressure supplied to the right hand ends-of the cylinders I2 through the conduits 46. This of courseY increasesthe clamping action to which the periphery..ofthe blank is subjected -by the clamping ring portion 23 of the upper die 2|; butthe parts are. so adjustedr and arranged that the iblanklwillwnot :be torni asithe Llower die member I8 (which in the press illustrated may be on the order of twelve inches) maybe reduced to around two inches. f

Figure 3 indicates the approximate extent of upward movement of the platen and upper die member when the press is to be used for shallow drawing, with a short stroke of thev lower die member I8; and it will be appreciated the condition of` permanence of connection between the upper ends of the tension rods and the platen used in working with a short stroke of the lower die I8, may be attained either by the use of permanent connections between the upper, ends of the tension rods, gasin' Figure 1l, or by not unlatching the platen from the upper ends of the rods, which in effect results in a permanent connection between the tension rods and the platen.

In whichever way such permanence of connection is provided, and because the lower ends of the tension rods are operatively connected with thelower bars 3i), 35| of the toggle mechanisms, such mechanisms will be collapsed into the condition shown in Figure 2 as the platen is lifted; and will assume a position with the toggles approaching `a straight or in line condition, see Figure 6, as the platen and tension rcdsare permitted to descend by gravity. After the periphery of the blank to be drawn is clamped between the upper die `member and the lower clamping ring as aforesaid, further and the required clamping action isproduced by admitting a liquid under pressure to the right hand ends of the toggle operating cylinders I2 as willbe understood. The construction and operation of the latching and unlatching mechanism between the platen and the tension rods 26, 21, 28 and 29, there `being one such mechanism at each side of the press, is as follows: 'I'hat is, the numerals 41, 41 and 48, 48 designate pairs of reciprocating bars spaced apart from one another and having C-shaped washers 49, 5I) and 5I, 52 secured in place between their ends, see Figure 9, and which bars and washers are supported by ribs 53, 54 formed upon the upper side of the platen 22. Theseribs merge into bosses 55, 55 and 51, 58 at their ends which` have holes through which the tension rods extend; and these tension rodsfare threaded` at then upperiendsiandhave stops .59,.v6xupon the.

in Figures 2 and 4, the stops lie above the bosses A so as to permit the C-shaped washers to be moved to the left and into positions between the upper ends of the bosses and the lower ends of the stops. This excess, however, need be no more than is suicient to insure that movement of the C-shaped washers toward the left in Figure 2 shall not be prevented or interfered with by the lower ends of the stops. I

The pairs of bars 47, 41 and 48, 48 slide upon plates 6| which are supported by the ribs 53, 54 to which they are fastened by bolts 52 passing through gibs 63; and said bars and the C-shaped washers carried by them are actuated by pistons, one for each pair, operating within cylinders 64, 65 secured to the plates 6| said pistons serving to actuate piston rods 8E, 61 the outer ends of which are operatively connected with the pairs of bars through brackets 6B, 69, which are fastened to the bars and move with them. Stuiling boxes 1,0, are provided for the rods E5, 61; and liquid under pressure is supplied to and exhausted from the cylinders 64, 65 through suitable conduits 12, 13 leading into the ends thereof, the ilow of liquid being controlled by any suitable valve mechanism. The numerals 14 designate sleeves secured to the under side of the platen 22, as shown, one surrounding each tension rod and through which sleeves said rods extend; and l are guides, one upon each tension rod although only one of them is shown, see Figure 1, which guides are slidable within the sleeves. These guides remain within the sleeves 14 when the platen 22 is lowered and assume positions within the upper ends of the bosses 55, 5t, 5l' and 58 thus steadying the upper ends of the rods when the stops 59 and E0 (and the other two carried by the rods 28 and 29) lie above the upper ends of the bosses, and the C-shaped washers (see Figure 2) are about to be moved to the left beneath the stops.

The pairs of bars 41, 41 and 48, G8 and the C-shaped washers carried by them are moved in unison by the piston rods 56, 61, as will be understood, movement of the bars to the right, Figure 2, serving to move all four washers out of the paths of movement of the stops upon the rods, as appears in Figures 1 and 9; whereupon the platen 22 may be lifted by the hoist 25 into the position shown in Figure l. Movement of said parts to the left (after the platen has been lowered to grasp a sheet metal blank 24, as in Figure 4) will return the washers to the left hand position in which they are shown in Figure 2; and thereafter and as lost motion between the stops and the washers is taken up the stops come into contact with the washers; the toggle mechanisms are straightened as aforesaid, thus increasing the clamping action between the upper die member 2| and the lower clamping ring l1; and the lower die member |8 is forced upward by the plunger I9 lto draw or shape the sheet metal blank as illustrated in Figure 5.

While Figure l shows the platen 22 as lifted only to such an extent that the stops lie within the bosses the platen may be lifted higher than in that figure, thus providing a wider gap between the upper die member 2| and clamping ring I1; in which case the stops enter the sleeves 'I4 further than shown, and the steadying members 'I5 take up positions within the sleeves lower than the positions suggested in Figure 1. Thereafter, and as the platen is lowered the steadying members assume positions adjacent the upper ends of and act to steady the upper ends of the tension rods at the time when the C-shaped washers are moved into positions beneath the stops.

When my improved press is to be used for deeper drawing than is contemplated in the form thereof illustrated, as with a stroke of the plunger |9 and lower die member I8 approaching 12 inches as hereinbefore mentioned, the same lower blank clamping ring I1 is or may be used; but a thicker upper die member or one having a deeper recess is substituted for the die 2| shown. This substituted upper die member will be placed upon the clamping ring when the pairs of toggles 33, 34 are in a nearly straight or in line condition, as shown in Figure 6, and the several stops 59 etc., will be adjusted and secured to the tension rods in positions high enough so that the C- shaped washers may be moved in between the under sides of said stops and the upper ends of the abutments 55, 56, 51., 58; the platen 22 being in place and the upper die member being secured to the under side thereof as hereinbefore appears.

This completes the setting up of the press with a different upper die member, for producing sheet metal articles (such as panels) requiring a deeper depth of drawing of the blank 24 operated upon; and after the toggle mechanisms have been col lapsed to bring the stops above the abutments (as by lifting them by external means, by supplying a liquid under pressure to the left hand ends of the cylinders |2, or otherwise) the C-shaped washers may be moved in between the under sides of the stops and the upper ends of the abutments, as they are shown in Figure 2.

The press is now ready to carry out its cycle of operation. Liquid under pressure supplied to the right hand ends of the cylinders |2 straightens or nearly straightens the toggles and applies increased clamping pressure to the periphery of the sheet metal plate; the plunger |9 and lower die member are forced upward to draw or shape the blank, by liquid under pressure supplied to the cylinder I4; the platen is unlatched from the tension rods by supplying a liquid under pressure to the front ends of the cylinders 64, 65, thus permitting the platen to be lifted; and the platen is lifted by the hoisting mechanism 25 and the plunger I9 and lower die are lowered to permit the removal of the formed sheet metal panel from the press.

The liquid under pressure for operating the toggle mechanism, the lower die member, and the latching and unlatching mechanism is preferably but not necessarily supplied by a single pump, driven by an electric motor, both supported from and located beneath the bed I3; but inasmuch as the liquid supply system and the details of the valves for controlling the flow of the liquid are of general application in hydraulically operated as well as in other apparatus, such devices are not disclosed in this present application. Furthermore and so far as this present application is concerned the electrically operated hoist 25 may be controlled by any suitable switch device or mechanism.

Figure 12 is a view showing a form of my iinproved press wherein, as in the form illustrated in Figure 11, tension rods 292, 262 andtwo others as shown inFigure 6, extend through holes in the four corners of `the platen 22 2, and have nuts 223 in engagement'withthe platen so that itv moves up and down with the rods. In this form of my invention the electrically'operated hoist 25 or equivalent device for lifting the rods, the platen andthe upper die member, is dispersed with; upward movement of the platenvandtension rods being produced by a liquid under pressure supplied to the left `hand ends of the toggle operating cylinders |2, as hereinbefore explained. The construction and operation ofthe toggle mechanism itself is the same as illustrated in Figures l, 2, 6 and? and hereinbefore explained; the same being supported beneath a stationary bed |32 supported by a base |02, having arms |52 which support said bed as in the form of my invention rst herein described; the toggle mechanism being operated by a liquid under pressure supplied to the cylinders |2` through suitable conduits 46.

This form of my invention is one especially adapted for extremely shallow drawing, and makes use of a lower ring member |12 supported by the bed |32 and which is similar to the lower ring member but is enough thicker than saidv member to permitthe` sheet metal blank 242 to be forced downward thereinto to `an extent required by the panel or other device to be produced. The lowerdie member |8 may then Abe left in the press if the depth of drawing is not more than around two inches, the extent of down`` ward movement of the tension rods and the platen produced by the toggle mechanism; or may be removed from the press as it is not involved in the inordinately shallow drawing operation here contemplated.

In shallow drawing here contemplated due to downward movement ofthe platen and upper die member 2| 2 said upper die member is of less width or diameter than the die member 2| shown.

so that its lower end may enter the lower ring member |12 to an extentrequired by the shallow or slight depth .of drawing of the sheet metal blank here contemplated.

Having thus described and explained my invention I claim and desire to `secure by Letters Patent:

1. In a combinedtoggle and hydraulic press, a fixed lower blank clamping ringmember; a reciprocating lower die within vsaid ring member and movable upwardly therein ;A a vertically movable upper die member into which said lower die enters, and which die member has a clamping ring portion adapted to cooperate' with said lower ring member to clamp a sheet metal blank' between them; lifting means separate, structurally, from the press, for moving saidupper die member away from and `for returning it into engage` ment with the upper end `of said llower ring` member, to thereby preliminarilyclamp a sheet metal blank between the ring portion thereof and said lower ring member; toggle mechanism operated by said upper die member; means associated with said toggle mechanism for increasingthe clamping action aforesaid between said upper die member and said lower ring member;"a cylinder and means for supplying `a liquid under pressure thereinto; and a reciprocating plunger within said cylinder and operatively associated with said lower die,.and acting to force said dieupward and into said upper die member. f

2, In a combined toggle and hydraulic press,

a 'iixed lower blank `clamping ring member; a reciprocating forming die within said ring mem` ber .and :movable upwardly therein; a vertically movable upper die member into which saidforming die enters, and which member has vaclamping `ring portion adapted to cooperate with said lower ring member to clamp a sheet metalblank between them; lifting means separate, structurally, from the press, for moving said upperldie member awayfrom and for returning? it into engagement with the upper end of said lower clamping ring member; toggle mechanism operatedby said upper die member and acting to permit lsaid member to move downward into engagement with, to' thereby preliminarily clamp a sheet metal blank between the ring portion `thereof and said lower ring member; means independent oi said Vupper die member forincreasing the clamping action of said toggle mechanism upon the sheet metal blank aforesaid; .a cylinder and means for supplyinlg a liquid under pressure thereinto; and a reciprocating plunger within said cylinder and operatively associated with said lower forming die, and acting to force said die upward and into said` upper die member.

3l In a combined toggle and hydraulic press, 4a

fixed lower blank `clamping ring member; a reciprocating lower die memberwithin said ring member and movable upwardly therein; a vertically movable upper die member into which said lower die enters, and which die member has a clamping ring portion integral therewith and adapted to cooperate with said lower ring member to clamp a sheet metal blank between them; lifting means separate. structurally, from the press, for moving said upper die member away from and for returning it into engagement with the upper end of said lower Iclamping ring member; toggle mechanism operated by said upper die member and acting to permit movement of l said member downward, to thereby preliminarily clamp a sheet metal blank between the ring portion thereof and said lower ring member; lmeans operatively associated with said toggle mechanism and operated by a liquid under pressure for increasing the clamping action thereof upon said blank; a cylinder and means for supplying a liquid under pressure thereinto; and a reciprocating plunger within lsaid cylinder and operatively associated with said lower die, and acting to force said die upward and into said upper die member.

4. In a combined toggle and hydrauliepress, a base having a cylinder which is open at-its upper end; a `bed supported by said base and having a flat upper surface disposed adjacent the upper end of and ext-ending at right angles to the axis of said cylinder; a lowerblank clamping ring member supported upon said bed; a reciprocating lower die member within-said ring member and movable upwardly therein; avertically movable upper die member into which said lower die enters, and which upper die member is adapted to cooperate with said ring member to clamp a sheet metal blank between `them lifting means separate, structurally,l from ithe press, for moving said upper diemember away from and for returning it into engagement with the upper end of said ring member; toggle mech-V anism supported by and located beneath said bed, and which toggle mechanism is operatively 4connected with and acts to permit movement of said upper die member downward to thereby preliminarily clamp a sheet metal blank between said upper die member and 4said ring member; means supported by and located beneath said bed for operating said toggle mechanism to increase the clamping action aforesaid between said upper die member and said ring member; a reciprocating plunger within said cylinder and adapted to force said lower die upward; and a conduit for supplying a liquid under `pressure to said cylinder.

5. In a combined toggle and hydraulic press, a base having a cylinder which is open at its upper end; a bed supported by said base and having a flat upper surface disposed adjacent the upper end of and extending at right angles to the axis of said cylinder; a lower blank clamping ring member supported upon said bed; a reciprocating lower die member within said ring mem- ,l

' member downward to thereby preliminarily clamp a sheet metal blank between said upper die member and said lower ring member; means operated by a liquid under pressure for increasing the clamping action aforesaid between said u per die member and said ring member during upward movement of said lower die member; a reciprocating plunger within' said cylinder and adapted to force said lower die upward; and a conduit for supplying a liquid under pressure to said cylinder.

6. In a combined toggle and hydraulic press, a fixed lower blank clamping ring member; a reciprocating lower die within said ring members and movable upwardly therein; a vertically movable upper die member into which said lower die enters, and which upper die membervis adapted tovcooperate with said ring member to preliminarily clamp a sheet metal blank between them; a platen to the under side of which said upper die member is secured; a plurality of reciprocating tension rods depending from said platen;

mechanism carried by said platen for latching the upper ends of said rods and platen together, and for unlatching said platen from said rods; lifting means separate, structurally, from the press, for moving said platen and upper die member upward when said platen is unlatched from said rods; toggle mechanism located below said lower clamping ring member and with which the lower ends of said tension rods are connected; means operatively connected with said toggle mechanism for increasing the clamping action aforesaid between said upper die member and said lower ring member; a cylinder and means for supplying a liquid under pressure thereinto; and a reciprocating plunger within said cylinder and operatively associated with said lower die, and acting to force said die upward and into said upper die member.

v`'7. In a combined toggle and hydraulic press, a

fixed lower blank clamping ring member; a reciprocating lower die within said ring member and movable upwardly therein; a vertically movable upper die member into which said lower die enters'and which upper die member is adapted to cooperate with said ring member to preliminarily clamp a sheet metal blank between them; a platen to the under side of which said upper die member is secured; a plurality of reciprocating tension rods extending from below said clamping ring upward and through holes in abutments upon the upper side of said platen; stops secured one to each of said tension rods, and which stops are movable with said rods into positions above said abutments; a plurality of C- shaped washers; means for moving said washers into and out of positions between said stops and the upper ends of said abutments; lifting means separate, structurally, from the press, for moving said platen and upper die member upward when said C-shaped washers have been moved from between said stops and said abutments; toggle mechanism with which the lower ends of said tension rods are connected; means operatively connected with said toggle mechanism for increasing the clamping action aforesaid between said upper die member and said lower ring member; a cylinder and means for supplying a liquid under pressure thereinto; and a reciprocating plunger within said cylinder and operatively associated with said lower die, and acting to force said die upward and into said upper die member.

8. In a combined toggle and hydraulic press, a xed lower blank clamping ring member; a reciprocating lower die within said ring member and movable upwardly therein; a vertically movable upper die member into which said lower die enters, and which upper die member is adapted to cooperate with said ring member to preliminarily clamp a sheet metal blank between them; a platen to the under side of which said upper die member is secured; a plurality of reciprocating tension rods extending from below said clamping ring upward and through holes in abutments upon the upper side of said platen; stops secured one to each of said tension rods, and which stops are movable with said rods into positions above said abutments; a plurality of C- shaped washers; means operated by a liquid under pressure for moving said washers into and out of positions between said stops and the upper ends of said abutments; lifting means separate, structurally, from the press, for moving said platen and upper die member upward when said C-shaped washers have been moved from between said stops and said abutments; toggle mechanism with which the lower ends of said tension rods are connected; means operatively connected with said toggle mechanism and operated by a liquid under pressure for increasing the clamping action between said upper die member and said lower ring member; a cylinder and means for supplying a liquid under pressure thereto; and a reciprocating plunger within said cylinder and acting to force said lower die upward and into said upper die member.

' JOHN PAWLOSKI. 

